1. Field of the Invention
The invention relates generally to magnetically actuated, hermetically sealed, reed-type switches of the type that is actuatable in response to proximity to a magnetizable or permeable material and which is particularly useful in providing a totally sealed, weatherproof switch.
2. Description of the Prior Art
The prior art includes a number of different types of magnetic proximity switch utilizing reed switches or similar contact configurations for actuation in response to a magnetic field. Early types of magnetic switch consisted of a pair of contacts formed of magnetic material and physically disposed relative to a magnet to achieve desired switch closure. U.S. Pat. No. 4,038,620 provides a representative showing of one type of magnetic switch wherein the reed contacts are disposed directly between two magnet materials and influenced by relative movement to open and close reed contacts. This type of switch is characterized by the use of multiple magnets relatively positioned to influence the reed contacts.
U.S. Pat. No. 3,560,846 teaches still another configuration of plural magnets as utilized in a balanced manner to influence the contacts of a reed switch. This switch functions as a proximity detector to effect switch closure by saturating a high permeability yoke and concentrating the magnetic flux field to close the reed contacts. U.S. Pat. No. 4,210,888 teaches a relatively basic form of proximity switch wherein the magnet portion of the switch is movably displaced for proximity actuation of the reed switch for either normally open or normally closed operation. Finally, the U.S. Pat. No. 3,205,323 teaches a proximity switch that utilizes a specially formed ceramic magnet that is laterally polarized and including a flux passage hole through the middle. Reed switch operation is effected by concentration or disbursement of the magnetic flux field through the contacts as the magnet elements are all disposed in balanced relationship thereto.